1. Field of the Invention
The present invention relates to a refrigerated display cabinet. In particular, but not exclusively, the present invention relates to a refrigerated display cabinet having a housing defining a display chamber, at least one shelf mounted in the chamber for receiving items to be displayed, and a refrigeration system for circulating refrigerated air around the chamber. Refrigerated display cabinets are utilised in retail, catering and convenience establishments for storing chilled food or drinks, and for displaying the food or drink items in an attractive manner.
A wide range of different types of cabinets have been produced, to suit the needs of the various different establishments which utilise them. These include cabinets with open fronts through which food or drink items can be inserted and extracted; cabinets with open fronts through which food or drink items can be extracted and rear surfaces with doors for inserting items into the cabinet; cabinets with closed fronts which can be opened so that food or drink items can be inserted and extracted; and cabinets with closed fronts through which food or drink items can be viewed, the food or drink items inserted and extracted through doors in a rear surface of the cabinet.
In each case, the display cabinets have a housing defining a display chamber, a number of shelves mounted in the chamber for receiving items to be displayed, and a refrigeration system. The refrigeration system circulates air which has been cooled to below ambient room temperature around the chamber, to chill the food and drink items. The cabinet housings are shaped to promote air flow around the chamber, so as to reduce the loss of cooled air to the surrounding environment.
2. Description of the Related Art
Refrigerated display cabinets having front or rear surfaces with doors in them suffer from a particular problem of loss of cooled air. This is because the doors are opened whenever it is required to gain access to the chamber for inserting food or drink items into the display cabinet, and/or to remove food or drink items for purchase or serving, depending upon the design of the cabinet. It has been found that opening a door in a cabinet can cause a significant volume of cooled air to be lost into the surrounding environment, and warmer ambient air to enter. This has three significant disadvantages.
Firstly, when cooled air is lost through the open door, the circulation of cooled air within the chamber is disrupted, with the result that the temperature in the chamber is higher than desired during the time when the door is open. As a consequence, when the door is closed, the refrigeration system has to perform additional work in order to re-cool the air in the chamber to the required level. This leads to high energy usage and thus operating costs.
Secondly, the loss of cooled air into the surrounding environment, and the entry of warmer ambient air, also leads to an increase in the temperature of the air in the chamber. This is a particular problem as the cabinets are frequently used in areas where the ambient air temperature is relatively high. As a result, the temperature of the food or drink items in the cabinet may not be maintained at a sufficiently low level. This can lead to the food or drink items becoming too warm, with the result that they may at least be unpalatable, but that they may also present a danger to health, or may require to be disposed of earlier than would otherwise be the case.
Thirdly, the refrigeration system may include a compressor, which is an expensive component. The compressor functions to compress a coolant which, when it subsequently expands, creates a cooling effect which is utilised to cool the air flowing into the display chamber. The loss of cooled air into the surrounding environment, and the entry of warmer ambient air into the display chamber, results in the compressor having to do additional work to maintain the air in the chamber at the required temperature level. This puts additional strain on the compressor, and reduces its effective life so that it requires more regular maintenance than might otherwise be the case, and possibly early replacement.
These problems are exacerbated in high usage environments, where the doors are frequently being opened and closed. Furthermore, in prior cabinets, the doors have usually been a simple arrangement where the door(s) extend from top to bottom of the chamber, and open by sliding horizontally over one-another, to provide access into the chamber. Other cabinets have utilised simple hinged doors, which pivot about vertical hinge pins. In both cases, the result of this is that air is lost from the chamber when the door(s) are opened, as the chamber is open to the surrounding environment over its entire height. The sliding doors also only provide access to food or drink items on part of a length of the shelf or shelves in the chamber.